The central theory underlying most current research in human tumor immunology is the concept of Immune Surveillance. It proposes that there is a host component in the development of cancer. According to this theory cancers develop as the result of a somatic mutation or by an external transforming agent continuously but are rejected immuno-logically in normal individuals. In cancer patients the tumors are permitted to grow by an inadequacy or a blocking of the normal immune response. We propose to test this theory by quantitatively evaluating both the general and the tumor specific immune response in a population group (cervical dysplasia and early cervical carcinomas), in which the development of invasive clinical cancer is occurring in a known percentage of cases. Analytical techniques capable of assessing each aspect of the immune response are available. The investigation should be capable of determining whether immune surveillance can and does occur in humans and, if so, the nature of its failure in patients who develop cancer.